@riversflows I, too, would love a waterproof parasol and have been looking for one on and off for a while with no joy.
I have a lot of ordinary garden parasols and none are waterproof, a couple are showerproof-ish. I've even wondered about an awning but I'd prefer a parasol, or should that be a garden umbrella if its for rain? The awnings I've looked at don't specify being fully waterproof but you would think the more expensive ones might be?
I was inspired visiting Copenhagen in December, they have big waterproof parasols with heaters outside restaurants and cafes and sit out year round. It's lovely and cosy. We drank hot chocolate outdoors in heavy rain and totally got the meaning of hygge. The type they have are commercial, the sort of thing you might see in a pub beer garden, not really for home but perhaps some Danish manufacturers do waterproof domestic versions?
I looked at Jysk for this reason but theirs are water resistant to light rain and dew only. On offer now though so may be worth a look. Most other retailers don't mention any water resistance at all.
I have thought about adapting a huge golf umbrella before. Otherwise, there are fishing umbrellas and half tent-half umbrella type shelters. What I really want is a lovely traditional parasol that is also waterproof.
@menopausalmare great idea about the waterproof spray, might try that.